The present invention relates to the data processing field, and more particularly, relates to a method and computer program product for processing system files using a trigger program.
Many Database Management Systems (DBMS) use system files to store information used to process queries. These files must then be probed to extract that information before it is used. Since I/O operations are generally very expensive and DBMS are performance critical, any additional I/O requests to extract this information can influence the overall system performance.
Performing any additional I/O operation while processing-a query request can be very expensive, this is why many of the DBMS try to pre-process as many queries as possible and store the implementation (query plans) for those queries so they do not have to be re-calculated them at run-time. This is normally done at program compilation or bind time and that information is stored as part of the program itself. This works fine for those queries that can be interpreted once and re-used many times (statistic SQL), but when dealing with dynamic SQL, where the query plans must be generated each time the query is executed, the SQL Catalog tables and initialization files must all be accessed in order to extract the information required to generated an appropriate plan.
Other implementations have been devised to allow more queries to be calculated one time and have that query plan bound to the program itself. The SQL Call Level Interface API""s is one example of this implementation.
A need exists for a mechanism for processing system files to improve overall system performance in a computer system.
A principal object of the present invention is to provide a method and computer program product for processing system files. Other important objects of the present invention are to provide such method and apparatus for processing system files substantially without negative effects and that overcome many disadvantages of prior art arrangements.
In brief, a method and computer program product are provided for processing system files. An associated trigger program is attached to each respective system file. The associated trigger program is utilized for pre-processing the respective system file to identify predetermined information. The identified predetermined information is stored in an internal structure. The internal structure is utilized to access the predetermined information when required to perform a query.